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Vaginal bacterial load in the second trimester is associated with early preterm birth recurrence: a nested
L Goodfellow1, M C Verwijs2, A Care1
1Harris Wellbeing Research Centre, Department of Women's and Children's, Health, University of Liverpool, Liverpool, UK.
Summary
Increased vaginal bacterial load in high-risk women during the second trimester is linked to recurrent spontaneous preterm birth (sPTB) and preterm prelabour rupture of membranes (PPROM). Lactobacillus iners domination may increase recurrence risk.
Area of Science:
- Reproductive biology
- Microbiome research
- Obstetrics
Background:
- The vaginal microbiome (VMB) plays a crucial role in pregnancy outcomes.
- Recurrent spontaneous preterm birth (sPTB) and preterm prelabour rupture of membranes (PPROM) remain significant challenges in maternal-fetal medicine.
- Understanding the VMB's contribution to sPTB/PPROM recurrence is essential for developing targeted interventions.
Purpose of the Study:
- To investigate the association between vaginal microbiome composition and recurrent early sPTB/PPROM.
- To determine if specific VMB types or bacterial loads are predictive of recurrent adverse pregnancy outcomes.
Main Methods:
- A nested case-control study was conducted with high-risk women.
- Vaginal swabs were collected between 15 and 22 weeks' gestation.
- 16S rRNA gene sequencing and quantitative PCR were used to analyze VMB composition and bacterial load.
Main Results:
- Vaginal microbiome type and diversity were not associated with recurrence.
- Women with recurrent sPTB/PPROM exhibited a higher median vaginal bacterial load and estimated Lactobacillus concentration.
- Higher recurrence risk was associated with increased bacterial loads, particularly with Lactobacillus iners domination.
Conclusions:
- Elevated vaginal bacterial load in the second trimester is associated with recurrent early sPTB/PPROM.
- Vaginal dominance by certain lactobacilli, excluding L. iners, may offer protection against high bacterial loads.
- Future studies on preterm birth should incorporate quantification of vaginal bacteria and yeasts.
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